COLD START LIFTER NOISE AFTER COLD START

MODELS AFFECTED: 1987 ALLANTE

The port fuel injected HT4100 engine used exclusively in the 1987 Allante- incorporates hydraulic roller valve lifters. These lifters may exhibit a moderately deep tapping noise for 2-3 seconds after a cold start followed by a light ticking for several minutes. It is most likely to occur in colder ambient temperatures and may occur only intermittently. The condition is not harmful and is not generally noticeable inside the car.

Comments of this condition can be remedied by installing a set of new pushrods, P/N 1644842 (16 pieces required). This new pushrod entered Allante production at VIN 101635 and is 1mm longer than the P/N 1635095 pushrod it replaces (194mm/7.64" vs. 193mm/7.60"). The longer pushrod can be identified when new by a yellow paint stripe, however, the stripe is not a permanent mark and may not be visible after use. The shorter pushrod design is being replaced by P/N 1644842, both in production and service parts stock. Once the inventory of short pushrods is purged, the yellow identification stripe will be discontinued.

If pushrod replacement does not eliminate valve lifter noise on start-up, oil pump assembly P/N 3517635 may be installed in 1987 Allante engines before VIN 101635. Vehicles after this breakpoint should be built with oil pump P/N 3517635.

For warranty purposes, use labor operation J0587 at 2.1 hours.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.